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Preoperative Prediction of Mortality within 1-year after Elective Endovascular Aortic Repair of Aneurysms Involving the Renal-Mesenteric Arteries
Dean J Arnaoutakis¹, Dan Neal², Murray Shames¹, Adam W Beck³, Andres Schanzer⁴, David H Stone⁵, Salvatore T Scali^2
1University of South Florida, Tampa, FL;²University of Florida, Gainesville, FL;³University of Alabama at Birmingham, Birmingham, AL;⁴University of Massachusetts, Worcester, MA;⁵Dartmouth University, Lebanon, NH

Background: Treatment goals of prophylactic endovascular aortic repair of complex aneurysms involving the renal-mesenteric arteries(cEVAR) include achieving both perioperative success and long-term survival benefit. Mortality within the first postoperative year after cEVAR likely indicates ineffective therapy due to associated costs and procedural complexity. Currently, there are no validated clinical decision-aid tools that reliably predict mortality after cEVAR. The purpose of this study was to derive and validate a preoperative prediction model of 1-year mortality after elective cEVAR.
Methods: All elective cEVARs including fenestrated, branched and/or chimney procedures limited to proximal Ishimaru landing zones 6-8 in the SVS-VQI were identified(2012-2021). Patients(n=4,116) were randomly divided into training(n=3,087) and validation(n=1,029) data sets. A parsimonious model was derived using Cox regression and backward stepwise elimination. The model was internally validated by bootstrapping(1000-times) the C-statistic and by graphical comparison of predicted and observed survival. Independent predictors were assigned an integer score, based on model beta-coefficients, to generate a simplified scoring system to categorize patient risk.
Results: The overall crude 1-year mortality rate after elective cEVAR was 11.4%(n=469/4116). Independent preoperative predictors of 1-year mortality included chronic obstructive pulmonary disease(COPD: on oxygen or medications), renal insufficiency(creatinine >1.8mg/dL or on dialysis), hemoglobin<12g/dL, decreasing body mass index(BMI), congestive heart failure(CHF), increasing age, ASA>3, current tobacco use, functional status(limited to self/assisted care or bed bound), proximal disease extent, and female sex(Table). Depending on the number of risk factors present, 1-year mortality varied from 4%→33%. The validation data C-statistic was 0.7. Predicted vs. observed survival analysis demonstrated excellent ability to both discriminate risk and predict survival(Figure). The internally validated scoring system classified patients as low-risk(≤11), moderate-risk(12-18), high-risk(19-27), and extreme-risk(≥28)(Table). Among all patients, 50%(n=2,058/4,116) were categorized as either high- or extreme-risk with predicted and observed 1-year mortality of 10% and 25%, respectively. Aortic diameter was below SVS guideline recommended treatment thresholds(<5.0cm-female,<5.5cm-male) in 18%(n=727/4,092) of patients, 31% of whom were categorized as high-/extreme-risk. These poor-risk patients had significantly increased in-hospital complication(18% vs. 13%,p=.04) and 1-year mortality(13% vs. 6%,p=.0004) rates compared to low-/moderate-risk patients with appropriate aneurysm diameters(≥5.0cm-female,≥5.5cm-male).
Conclusions: This is the first description of a validated preoperative prediction model for cEVAR 1-year mortality that accounts for physiological, anatomical, and functional variables. Notably, half of patients who underwent cEVAR had a high predicted 1-year mortality rate, which would suggest a significant opportunity to optimize patient selection paradigms to best identify those most likely to derive benefit from cEVAR. This novel and simplified scoring system can effectively discriminate mortality risk and when applied, may improve preoperative decision making, complex aneurysm care delivery, and resource allocation.
Table. Independent Predictors of 1-Year Mortality after Complex EVAR and Risk Score Assignment

Preoperative Factor	HR (95% CI)	P-value	Risk Score if Present	Risk Categories with Predicted 1-year Mortality
COPD on home oxygen	2.3 (1.7,3.3)	<.0001	+9	Score ≤11Low-Risk1-yr mortality: 2%
COPD on medication	1.6 (1.2,2.0)	.0002	+5
Creatinine >1.8 mg/dL or dialysis	2.0 (1.5,2.7)	<.0001	+7
Hemoglobin <12 g/dL	1.6 (1.2,2.0)	.0002	+5
				Score 12-18Moderate-Risk1-yr mortality: 5%
BMI (kg/m2)	HR multiplies 0.96 for each unit increase (0.94, 0.98)	.0004	-40% of BMI
Congestive heart failure	1.7 (1.3, 2.2)	<.0001	+6
Age	HR multiplies 1.02 for each year(1.0, 1.04)	.0003	+30% of Age
				Score 19-27High-Risk1-yr mortality: 10%
ASA class 4 or 5	1.5 (1.2, 1.8)	.0006	+4
Current smoker	1.4 (1.1, 1.8)	.004	+4
Functional status = self-careassisted care or bed bound	1.4 (1.1, 1.8)	.009	+4
				Score ≥28Extreme-Risk1-yr mortality: 25%
Female sex	1.3 (1.03, 1.6)	.03	+3
Disease extent limited to Zone 9	0.8 (0.6, 0.9)	.05	-3

Figure. Comparison of Predicted and Observed Survival for Each Risk Group

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